The present invention is concerned with seals employed to seal the piston of a hydraulic motor to the wall of a cylinder bore in applications where high working pressures or pressure surges may be encountered.
In the past, designers of piston seals held different opinions as to whether metal piston rings or seals of resilient material provided the better seal. Advocates of the resilient seal contended that metal piston rings, due to minor imperfections in the cylinder bore and wear of the relatively soft metal ring, would inevitably permit some fluid bypass. Those who preferred the metal ring contended the resilient seal, because of its resilience, could not always successfully resist shock loading or abnormally high-pressure surges. For applications where normally encountered working pressures would be high, the standard approach was to simply increase the number of metal rings or resilient seals employed.
The present invention is directed to a piston seal arrangement which, with a minimum number of seals, is extremely resistant to fluid bypass occasioned by cylinder bore imperfections or wear of the seal and is, at the same time, substantially insensitive to high-pressure surges. The seal is especially designed for use in applications where extremely high working pressures are encountered.